There are many situations where particulates are entrained in a liquid. One example includes production fluid from wells in the oil and gas industry, which often contain particulates such as sand. These particulates could be part of the formation from which the hydrocarbon is being produced, introduced particulates from hydraulic fracturing or fluid loss material from drilling mud or fracturing fluids or from a phase change of produced hydrocarbons caused by changing conditions at the wellbore (asphalt or wax formation). As the particulates are produced, problems occur due to abrasion, and plugging of production equipment. In a typical startup after stimulating a well by fracturing, the stimulated well may produce sand until the well has stabilized, often for a month or up to many months after production commences. Other wells may also require extended use of a desander. In this document the term “sand” is used as is common in the industry to include solid particles that are entrained in the production fluid, the majority of which is generally sand, but may contain other substances as well.
In the case of gas wells, fluid velocities can be sufficiently high that the erosion of the production equipment can result in catastrophic failure. High fluid stream velocities are typical and are even purposefully designed for elutriating particles up the well and to the surface. An erosive failure of this nature can become a serious safety and environmental issue for the well operator. A failure such as a breach of high pressure piping or equipment releases uncontrolled high velocity flow of fluid which is hazardous to personnel and equipment. Release to the environment is damaging to the environment resulting in expensive cleanup and loss of production. Repair costs are also high.
In all cases, retention of particulates contaminates both surface equipment and the produced fluids and impairs the normal operation of the oil and gas gathering systems and process facilities.
One prior art system that attempts to separate solid particulates from a multi-phase flow can be found in U.S. Pat. No. 7,383,958 (Hemstock et al.) entitled “Desanding apparatus and system”. This design uses a weir plate within a vessel to direct the flow downward and maintain a gaseous volume above. Another example of a prior art system can be found in U.S. Pat. No. 7,785,400 (Worley et al.) entitled “Spherical Sand Separators”, which separates natural gas from productions streams of water, sand and natural gas.